This invention relates to a marking apparatus for marking the surface of a device for discrimination, more specifically to a marking apparatus for stamping a mark on the surface of a plastic encapsulated semiconductor device.
Generally, the surface of a plastic encapsulated semiconductor device carries oils and fats or oozes with a mold release agent. In particular, a mold release agent is commonly used in plastic encapsulation to facilitate release of a plastic encapsulated semiconductor device from a mold. The surface of such a plastic encapsulated semiconductor device must be stamped with a mark for discrimination. In such stamping, however, oils, fats, or mold release agents act as marking-obstructive substances which, if remaining on the surface of the device, will destroy satisfactory stamping conditions.
Conventionally, therefore, a pretreatment process for removing the oils, fats, or mold release agents from the surface of the device is executed before the stamping process. In the pretreatment process, as shown in FIG. 1 for example, an abrasive 16 is blown against the plastic surface 12 of a semiconductor device 10 to be stamped by means of a honing nozzle 14, and the surface 12 is cleaned to remove oils, fats or mold release agents. Alternatively, in this pretreatment process, the plastic surface 12 is cleaned to remove the oils, fats, or mold release agents by means of cloth or cotton 20 impregnated with an organic solvent 18, as shown in FIG. 2.
In the pretreatment process, moreover, cleaned semiconductor devices 10 are manually set in a marking apparatus one by one. Therefore, the conventional system is extremely low in productivity, and hence suffers from the problem of high cost of products.